Friction draft gear



Dec. 24, 1957 s CAMPBELL 2,817,445

FRICTION DRAFT GEAR Filed June 17, 1955 I 4 Sheets-Sheet l IN VEN TOR.

Dec. 24, 1957 s, CAMPBELL 2,817,445

FRICTION DRAFT GEAR 4 Sheets-Sheet 3 Filed June 17, 1953 III!!! 7/ DeCQ24, 1957 D. s. CAMPBELL FRICTION DRAFT GEAR 4 Sheets-Sheet 4 Filed June 17, 1953 INVENTOR.

nited rates Patent FRICTION DRAFT GEAR David S. Campbell, Glen Ellyn, Ill., assignor to Cardwell Westinghouse Company, a corporation of Delaware Application June 17, 1953, Serial No. 362,228

6 Claims. (Cl. 213-32) This invention relates to draft gears for railroad cars and has for its principal object to provide a gear having high capacity in which the energy absorption increases as the gear closes, and the recoil on release is controlled by energy-absorbing resistance.

Generally speaking, this is accomplished by combining a cushioning element of the rubber spring type with a friction cushioning element in tandem.

Further objects and advantages of the invention will be apparent as the description is read in connection with the accompanying drawings, in which:

Fig. 1 is a horizontal section through familiar parts of a freight car, showing the draft gear applied;

Fig. 2 is a vertical section of the same;

Fig. 3 is an enlarged horizontal section through the draft gear and portions of the draft rigging showing the gear in full release;

Fig. 4 is a similar view showing the draft gear compressed in bufi;

Fig. 5 is a vertical section through the draft gear and associated followers, the draft gear being in full release as shown in Fig. 3;

Fig. 6 is a similar view of the draft gear being compressed in buff as shown in Fig. 4;

Figs. 7 and 8 are transverse sections on the lines 77 and 8-8 of Fig. 5;

Fig. 9 is a perspective view of the draft gear housing;

Fig. 10 is a perspective view of the plunger; and

Fig. 11 is a perspective view of friction plates, friction shoes, and a spring seat used in the friction cushioning element.

But these drawings and the corresponding description are for the purpose of illustrative disclosure only, and are not intended to impose unnecessary limitations on the claims.

In Figs. 1 and 2, the draft gear, indicated generally at 10, is shown in the familiar surroundings of center sills 11, draft gear lugs 12, draft yoke 13, coupler butt or shank 14, draft key 15, coupler carrier iron 16, draft gear carrier iron 17, coupler horn 18, and striking plate 19 (all corresponding to Fig. 10.51 of Car Builders Cyclopedia, 1946, p. 944). These parts are so familiar that no specific description is deemed necessary.

The draft gear housing, generally indicated by 20, includes a rear chamber 21 for a cushioning element of the rubber spring type, a front chamber 22 for a friction cushioning element in open communication with the rear chamber and open at the front.

A cushioning element, generally indicated by 23, including rubber spring units 24 and spacers 25 is in the rear chamber 21, along with a follower 26 at the front.

In the front chamber there is a friction cushioning element, generally indicated by 27, including a plunger 28 (Fig. 10) in thrust relation to the follower 26 and having opposite wedge surfaces 29, together with friction shoes 30 having wedge surfaces 31 cooperating with the wedge surfaces 29 on the plunger and stationary friction plates 32 in the front chamber 22 of the housing.

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The plunger 28 (Fig. 10) includes two arms 33 extending rearwardly from the wedge surfaces 29 and connected by a spring seat 34 which comes against the front face of the follower 26, as appears in Figs. 3 through 6.

A relatively light inner spring 35 extends between the follower 26 and the flat face 36 of the plunger and acts to urge the plunger away from the follower 26 toward release position. Its inner end extends through an opening 37 in the spring seat 34.

A relatively heavy outer spring 38 extends between the spring seat 34 and a beveled spring seat 39 cooperating with the inclined surfaces 40 on the wedges 30 and maintains a predetermined constant loading on the friction elements at all times. It also urges the wedges toward release position.

The rubber spring units 24 of the cushioning element 23 are composed of rubber blocks 41 (Fig. 8) vulcanized to opposite sides of the plates 42 and extending through them, as indicated at 43. A variety of such cushioning units are known, and no detailed description is deemed necessary. Specifications on the order of those given in Tucker Ser. No. 223,746, filed April 30, 1951, now Patent No. 2,720,319, issued October 11, 1955, may be used.

The rear chamber 21 of the housing is of generally box form, including a rear wall 44, side walls 45, front wall 46, bottom 47 and top 48 (Fig. 8); but the latter is in the main removed to permit the parts of the rubber cushioning element to be inserted from above to a position on the bottom 47, which may be partly open to promote self cleaning.

The front chamber, as here shown, is a reduced extension of the rear chamber beyond the front wall 46 and is provided with recesses 50 to receive the stationary friction plates 32.

After the parts of the gear are assembled substantially as shown in Figs. 3, 4, and 5, the gear is compressed slightly to align the openings 51 and 52 (Fig. 3) in the front housing 22 and the plunger 28 when a shear pin is inserted to hold the gear in sufiicient compression to make it short enough for free entry into a familiar draft gear pocket between the draft gear lugs 12 and the sills 11.

The first normal operating force in a train will shear the pin, and afterwards the normal release position of the gear in the pocket will be substantially shown in Fig. 3.

In operation, upon receiving the boiling force, the parts move from the position shown in Fig. 3 toward that shown in Fig. 4, which is the limit of the compression. During this, the cushioning element 23 and the friction element 27 combine to absorb the energy of the shock. Upon release, the rubber, springs and the steel springs 35 and 38 urge the parts back toward the position shown in Fig. 3, and the recoil is controlled by the friction element which absorbs the energy of recoil.

This action arises from the inherent relationship between the rubber spring unit 23 and the coil springs 35 and 38. It is Well known in the art that when rubber is compressed, it follows a nonlinear, load-deflection curve, and since the rubber spring 23 is of relatively high capacity, upon release it expands first and dissipates the energy stored therein through the friction system. The coil spring 35, being of relatively light capacity, releases last to fully release the gear.

In draft, the yoke 13, carrying the housing 20 to the left in Figs. 3-6, compresses the cushioning element 23 against the follower 26, which is prevented from moving to the left by the plunger 23 and the standard follower 53 bearing against the front draft gear lugs 12.

I claim:

1. In a draft gear for mounting in the draft pocket of a railway car, said pocket having front and rear stops:

a housing having laterally spaced opposed friction surfaces therein; and a cushioning mechanism supported within said housing to react between said front and rear stops and comprising a cushioning unit, an intermediate follower, and an energy. absorbing friction system mountedin tander'n'with' said cushionin unit for series action therewith'and comprising a plunger member'having opposite wedge faces, 'said plunger member including a longitudinally offsets'pring seat'reactin'g against said intermediatefoll'o'wer, and opposed friction shoeshaving Wedge surfaces engaging the'face's of said plunger'andhaving'friction surfaces for engaging said'first-mentioned friction suffaces, resilient means reacting between said spring seat and additional wedge surfaceson said "shoes,'said additional wedge surfaces being inclined oppositely to said first mentioned wedge surfaces such'that' said resilient means continuously urges said shoes laterally outwardly into frictional engagementwith' said first-mentioned frictionsurfaces, said shoes being movable longitudinally inwardly relative to said housing as the plunger is advanced during compression of said gear and longitudinally outwardly relative to said housing during release of said gear. 2. In a draft gear for mounting in the draft pocket of a railway car, said pocket having front and rearstops: a housing having laterally spaced opposed friction surfaces mounted therein; and a cushioning mechanism supported within said housing to react between said front and rear stops and comprising a cushioning'unit, an intermediate follower; and an energy absorbing friction system mounted in tandem with said cushioning unit for series action therewith and comprising a plunger member having opposite wedge faces, said plunger member including a longitudinally offset spring seat reactingagainst said intermediate follower, and opposed friction shoes having wedge surfaces engaging the faces of said plunger and having fric' tion surfaces for engaging said first-mentioned friction surfaces, resilient means reacting between said spring seat and additional wedge surfaces on said shoes, said additional wedge surfaces being inclined oppositely to said first mentioned wedge surfaces such that said resilient means continuously urges said shoes laterally outwardly into frictional engagement with said first-mentioned friction surfaces, said shoes being movable longitudinally inwardly relative to said housing as the plunger is advanced during compression of said gear and longitudinally outwardly relative to said housing during release of said gear, and additional resilient means, of small capacity as compared to said cushioning unit, reacting between the plunger and said intermediate follower and urging the plunger longitudinally away from said intermediate follower toward full release position for said friction system, whereby upon release of the gear the recoil energy is partially absorbed by said friction system, after which said additional resilient means releases said friction system.

3. In a draft gear for mounting in the draft pocket of a railway car, said pocket having front and rear stops, a housing having a rear chamber and a front chamber in open communication with said rear chamber, said housing being of a length appreciably less than the distance between said stops and being mounted in the draft pocket for longitudinal movement therein, the front chamber of said housing having laterally spaced opposed friction surfaces therein; and a cushioning mechanism supported within said housing to react between said front and rear stops and comprising a cushioning unit of the rubber spring type and an intermediate follower disposed in said rear chamber, and an energy absorbing friction system disposed in said front chamber and mounted in tandem with said cushioning unit for series action therewith and comprising a plunger member having opposite wedge faces, said plunger member including a longitudinally offset spring seat reacting against said intermediate follower, and opposed friction shoes having wedge surfaces engaging the faces of said plunger wardly into frictional engagement with said-first mentioned friction surfaces, resilient means reacting between said spring seat and additional wedge surfaces. on'said shoes, said additional wedge surfaces-being inclined oppo sitely to said first mentioned wedge surfaces such that said resilient means continuously urges said shoes laterally outwardly into frictional engagement with said first-mentioned friction surfaces, said shoes being movable longitudinally inwardly relative to said housing during compression of said gear and longitudinally outwardly relative to said housing during release of said gear, and additional resilient means, of small capacity as compared to said cushioning unit, reacting between theplunger and said intermediate follower and urging the plunger longitudinally away from said intermediate follower toward full release position for saidfriction system, whereby upon release of the gear th'erecoil energy is partially absorbed by said friction system, after which said additional resilient means releases said 'frictionsystem.

4. In a draft gear for mounting in the draft pocket of a railway car, said pocket having front and rear stops: a housing having laterally spaced opposed friction surfaces therein; and a cushioning mechanism supported within said housing to react between said front and rear stops and comprising a cushioning unit, an intermediate follower, and an energy absorbing'friction system mounted in tandem with said cushioning unit for series action therewith and comprising a plunger having wedge shaped faces, opposed friction shoes having wedge surfaces engaging the faces of said plunger and having friction surfaces for contacting said'first-mentioned friction surfaces, said cushioningmechanism including means urging the wedge surfaces of said shoes against the wedge faces of said plunger such that-said shoes are urged laterally outwardly into frictional engagement with said first-mentioned friction surfaces, said shoes being movable longitudinally inwardly relative to said housing as the plunger is advanced dur-ing compression of said gear and longitudinally outwardly relative to said housing during release of said gear and resi'lient means, of small capacity as compared to said cushioning unit, reacting between the plunger and said intermediate follower and urging the plunger longitudinally away from said intermediate follower toward full release position for said friction system, whereby upon release of the gear the recoil energy is partially absorbed by said friction system, after which said additional resilient means releases said friction system.

5. In a draft gear for mounting in the draft pocket of a railway car, said' pocket having front and rear stops, a housing .having'a rear chamber and a front chamber in open communication with said rear chamber, said housing being of a length appreciably less thanthe distance between said stops and being mounted in the draft pocket for longitudinal movement therein, the front chamber of said housing-having laterally spaced opposed friction surfaces'therein; and a cushioning mechanism supported within said housing to react between said front and rear stops and comprising a cushioning unit of the rubber spring type and an intermediate follower disposed in said rear chamber, and an energy absorbing friction system disposed in said front chamber and mounted in tandem with said'cushioning unit for seriesaction therewith and comprising a plunger-having wedge shaped faces, opposed friction shoes-having wedge surfaces engaging the faces of said plunger and having friction surfaces for contacting said first-mentioned friction surfaces, said cushioning mechanismincluding-means urging the wedge surfaces of said shoes against the wedge faces of said plunger such that said shoes are urgedlaterally outwardly into frictional engagement with said first-mentioned friction surfaces, said shoes being movable longitudinally inwardly relative to said housing during compressionof said gear and longitudinally outwardly relativeto said housing during release of said gear, and resilient means, of small capacity as compared to said cushioning unit, reacting between the plunger'and said intermediate follower and urging the plunger longitudinally away from said intermediate follower toward :fullrelease position for said friction system, whereby upon release of the. gear the recoil energy is partially absorbedlby said frictionsystem after which said additional resilient means releases said friction system.

6. In a draft gear for mounting in the draft pocket of a railway car, said pocket having front and rear stops: a housing having laterally spaced opposed friction surfaces therein; and a cushioning mechanism supported within said housing to react between said front and rear stops and comprising a cushioning unit of the rubber spring type, an intermediate follower, and an energy absorbing friction system mounted in tandem with said cushioning unit for series action therewith and comprising a plunger member having opposite wedge faces, said plunger member including a longitudinally ofiset spring seat reacting against said intermediate follower, and opposed friction shoes having wedge surfaces engaging the faces of said plunger and having friction surfaces for engaging said first-mentioned friction surfaces, resilient means reacting between said spring seat and additional wedge surfaces on said shoes, said additional wedge surfaces being inclined oppositely to said first-mentioned wedge surfaces such that said resilient means continuously urges said shoes laterally outwardly into frictional engagement with said first-mentioned friction surfaces, said shoes being movable 10ngitudinally inwardly relative to said housing as the plunger is advanced during compression of said gear and longitudinally outwardly relative to said housing during release of said gear, and additional resilient means, of small capacity as compared to said cushioning unit, reacting between the plunger and said intermediate follower and urging the plunger longitudinally away from said intermediate follower toward full release position for said friction system, whereby upon release of the gear the recoil energy is partially absorbed by said friction system, after which said additional resilient means releases said friction system.

References Cited in the file of this patent UNITED STATES PATENTS 1,225,715 Johnson May 8, 1917 1,298,778 OConnor Apr. 1, 1919 1,403,617 Moore Jan. 17, 1922 2,203,542 Page June 4, 1940 2,282,171 Dean May 5, 1942 U. S. DEPARTMENT OF COMMERCE PATENT OFFICE CERTIFICATE OF CORRECTION Patent No 2,817,445 December 24, 1957 David S Campbell It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Let ters Patent should read as corrected below.

Column 3, into frictional line 25, strike out "mounted"; line '72, strike out "wardly having friction engagement with said-first menand insert instead -.--and surfaces for engaging said first-men- Signed and sealed this 4th day of March 1958,

(SEAL) Attest:

KARL H AXLINE ROBERT C WATSON Attesting Officer Commissioner of Patents 

